1. Field of the Invention
The present invention generally relates to a multimedia copy control system and method using a digital data recording medium, and in particular, to an optical disc reproducing apparatus in combination with a digital data recording apparatus, adapted to control duplication of digital data, preventing unauthorized duplication of contents in an optical disc on which multimedia data including digital video data and digital audio data is recorded.
2. Description of the Prior Art
In recent years, DVD (Digital Versatile Disc)-Video, DVD-Audio and the like with dramatically improved recording capacity have come into use in place of conventional laser disc and video CD, and a number of movie titles and music titles have been released in DVD. High quality digital audio data or digital video data is recorded on these DVD-Video standard disc and DVD-Audio standard disc, and because the digital data is of high quality, AV equipment makers have not taken measure of outputting digital signal data from the inside to the outside of the equipment from the fear that unauthorized digital copy is made. This is because contents providers who produce movie titles and music titles and provide such titles would be significantly damaged if digital copying is made and a number of unauthorized copy discs appear on the market.
In a conventional audio equipment, such as for example, CD (compact disc) player or MD (mini disc) player, digital audio data is outputted outside the equipment by using IEC60958 as a digital I/F. This IEC60958 includes generation copy control management information called CGMS (Copy Generation Management System) and controls the generation copy control management information so that even in the case where digital copy is permitted, digital copy of first generation is allowed for an unlimited number of times, whereas digital copy of second generation is prohibited. However, there has been a drawback that if someone tampers with a CGMS generation copy control management device of a recorder side, digital copies of unlimited generations can be easily produced.
FIG. 14 shows an outline of a reproducing/recording system in a conventional system of DVD. An authorized optical disc player 209 comprises: an encryption decoder 203 for decoding an encryption from a system stream; a reproduction controller 204 for servo-controlling an optical pickup and a working mechanism relating to reproduction of an optical disc; an AV decoder 206 for converting a system stream to a digital audio or digital video signal; an analogue output circuit 207 for converting the digital audio or the digital video signal into an analogue signal to output the analogue signal; and a digital output circuit 208 for converting the digital audio or digital video signal into a signal of a definite output format (for example, IEC60958, IEEE1394 and the like) to output the digital signal.
Meanwhile, an authorized optical disc recorder 216 comprises: an analogue input circuit 210 for converting an analogue audio or video input signal into a digital signal; a digital input circuit 211 for converting an input signal which is input in a definite digital format into a digital audio or digital video signal; an AV encoder 212 for converting the digital audio or digital video signal into a system stream; a recording controller 213 for servo-controlling an optical pickup and an working mechanism relating to recording of an optical disc; copy control management data (CCI) detector/rewriter 214 for detecting copy control management information from the system stream and rewriting it as necessary; and an encryption generator 215 for adding an encryption to the system stream. As for an commercially available press disc 201, the authorized optical disc player 209 reproduces an audio or video signal, which is digitally or analoguely connected to the authorized optical disc recorder 216 for creating a copy disc 202.
A case of authorized two generation recording in this conventional system will be described with reference to FIG. 15. It is assumed that only digital copy control information (hereinafter, referred to as digital CCI or “DGCCI”) is recorded in a predetermined form on a commercially available press disc 220, and the commercially available press disc 220 is under the condition with limitation that permits only one generation copy. This copy control management information is shown by a block 250. In other words, in this commercially available press disc 220, C parameters as shown in FIG. 10 indicate a status “C4=1, C3=0” (hereinafter, expressed by “C4C3=10”). When reproducing the commercially available press disc 220 with an authorized optical disc player 228, a digital output circuit 227 converts a digital audio or digital video signal into a signal of a definite digital output format to output the digital signal.
When the digital signal outputted in the definite digital format is inputted to an authorized optical disc recorder 235 from the authorized optical disc player 228, the inputted digital signal is converted into a digital audio or digital video signal by a digital input circuit 230. The converted digital audio or digital video signal is then converted into a system stream by means of an AV encoder 232. With the system stream, a copy control management data (CCI) detector/rewriter 233 detects the digital CCI (250) and determines the status to be “C4C3=10” that permits one generation copy and thus rewrites the C3 parameter of the digital CCI from 0 to 1 to make it into “C4C3=11” so as to prohibit copy of second and subsequent generations. An encryption generator 234 then adds an encryption to the system stream and a recording operation is performed under a control of a recording controller 231, whereby a first generation copy disc 221 is created. The resultant copy controlling management information of this case is shown by a block 251.
When reproducing the copy disc 251 by an authorized optical disc player 242, even though C parameters of the digital CCI have “C4C3=11” indicative of copy being prohibited, the reproduction is performed by the optical disc player 242 to output a system stream digital signal. The reason why the player normally performs a reproducing operation without stopping the reproduction even if copy is prohibited is that, it is impossible to authorize equipments to be connected, and the equipments to be connected to the digital output circuit are not limited to the recorder but may be an audio/video reproducing equipment with a digital input (such as for example, digital TV and digital amplifier). When this reproduced digital signal is inputted to an authorized optical disc recorder 249, a copy control management data (CCI) detector/rewriter 247 detects the digital CCI (251) to determine that copy is prohibited and does not perform a recording operation. As a result of this operation, a copy disc of second generation is not created.
However, when the copy control management data detector/rewriter (233) of the optical disc recorder (235) is tampered with, unauthorized copy becomes possible in the following manner. A case of unauthorized two generation digital recording in the same conventional system will be describe with reference to FIG. 16. Likewise the commercially available press disc 220, an commercially available press disc 260 is under the condition with limitation that permits only one generation copy, digital CCI satisfies “C4C3=10” and copy controlling management information thereof is shown by a bock 293. When reproducing the commercially available press disc 260 with an authorized optical disc player 269, a digital output circuit 268 converts a digital audio or digital video signal into a signal of a definite digital output format to output the digital signal.
When the digital signal outputted in the definite digital format is inputted into an unauthorized optical disc recorder 278 from the authorized optical disc player 269, the inputted digital signal is converted into a digital audio or digital video signal by a digital input circuit 271. The converted digital audio or digital video signal is then converted into a system stream by means of an AV encoder 273. For the system stream, a tampered copy control management data (CCI) detector/rewriter 274 detects the digital CCI (293) having “C4C3=10” that permits one generation copy. The tampered copy control management data detector/rewriter 274 tampers the digital CCI data to set for copy free “C4C3=00” though it should rewrite the C3 parameter of the digital CCI from 0 to 1 to make it into “C4C3=11” so as to prohibit copy of second and subsequent generations. Then, an encryption generator 276 adds an encryption to the system stream, and a recording operation is performed under a control of a recording controller 272, whereby a one generation copy disc 261 of copy free having no limitation for copy is created. Copy controlling management information of this case is shown by a block 294.
Since the digital CCI data of the one generation copy disc 261 is tampered to copy free, when this disc 261 is reproduced by an authorized optical disc player 285, a digital output circuit 284 converts a digital audio or digital video signal into a signal of a definite digital output format and outputs the digital signal. When the digital signal outputted in the definite digital format from the authorized optical disc player 285 is inputted to an unauthorized optical disc recorder 292, since the digital CCI data is set to copy free “C4C3=00”, digital copy discs of unlimited generations will be created. Copy control management information at this time is shown by a block 295. In other words, in the conventional system, once an unauthorized copy disc is created by means of a tampered unauthorized optical disc recorder, a copy free disc is to be created because of such an unauthorized copy disc even in the case of using an authorized optical disc player and authorized optical disc recorder.
A case of an authorized two generation analogue recording in this conventional system will described with reference to FIG. 17. Assuming that a commercially available press disc 300 is under the condition of copy prohibition, digital CCI satisfies “C4C3=11” and copy controlling management information thereof is shown by a block 331. When reproducing the commercially available press disc 300 with an authorized optical disc player 309, an analogue output circuit 307 outputs an analogue audio or analogue video signal, and a digital output circuit 308 (although not connected to a recorder) converts a digital audio or digital video signal into a signal of a definite digital output format to output the signal.
When the analogue signal outputted from the authorized optical disc player 309 is inputted to an authorized optical disc recorder 316, the inputted analogue signal is converted into a digital audio or digital video signal by means of an analogue input circuit 310. The converted digital audio or digital video signal is then converted into a system stream by means of an AV encoder 313. Since this converted system stream does not include digital CCI data, copy management information does not exist. Therefore, it is impossible to manage copy by means of a copy control management data (CCI) detector/rewriter 314. Moreover, since the input signal is analogue signal, no encryption is added to the system stream by means of an encryption generator 315, and a recording controller 312 performs a recording operation without adding an encryption, whereby a first generation copy disc 301 having no copy management information is created.
This copy disc 301 can be reproduced when reproduced by means of an authorized disc player 323, and because of absence of copy management information, it is possible to perform analogue recording or digital recording also by using an authorized optical dies recorder 330. That is, in the conventional system, even in the case of using an authorized optical disc recorder which is not tampered with, by creating a copy disc once by performing analogue recording, copy free discs allowing digital recording or analogue recording will be unlimitedly created even by using an authorized optical disc player or authorized optical disc recorder.
Now, with reference to FIG. 18, a detail block of the reproducing-recording system in the conventional case will be explained, and then explanation on digital recording operation and analogue recording operation will be made.
An optical disc player 352 comprises: a spindle motor 341 for rotating a disc 340; an optical pickup 342 for reading a signal recorded on the disc 340; a mechanism control section 343 for driving and controlling the spindle motor 341 and the optical pickup 342; a signal processing section 344 which extracts a system stream digital signal by performing data punching or error correcting of the output of the optical pickup 342 and supplies a control signal to the mechanical control section 343; an encryption decoder 345 for decoding an encryption from the system stream; an AV decoder 347 for extracting a digital audio or digital video signal from the encryption-decoded system stream and decoding the digital audio or video signal; a DA converter 348 for converting the digital audio or digital video signal into an analogue audio or analogue video signal; a digital signal output control section 349 for converting the digital audio or digital video signal into a signal of a definite output format (for example IEC60958, IEEE1394 and the like) to perform output control; an analogue signal output control section 350 for performing output control of the analogue audio or analogue video signal; and a system controller 351 for controlling the digital signal output control section 349 and analogue signal output control section 350 while reading the digital CCI data, as well as for controlling the mechanism control section 343.
Meanwhile, an optical disc recorder 365 comprises: a spindle motor 354 for rotating a recordable disc 353; an optical pickup 355 for recording a signal encoded by a recording signal processing section 357 on the recordable disc 353; a mechanism control section 356 for driving and controlling the spindle motor 354 and the optical pickup 355; the recording signal processing section 357 for outputting a recording signal to the optical pickup 355 while adding an error correcting code to a system stream on which an encryption has been added and performing modulation on the same, and for supplying a control signal to the mechanism control section 356 at the time of recording; a digital input converting section 360 for converting a definite digital signal outputted from the outside into a digital audio or digital video signal; an AD converter 359 for converting an analogue audio or video input signal into a digital signal; an AV encoder 361 for encoding the digital audio or digital video signal into a system stream; a digital CCI decoder 358 for detecting digital CCI from the system stream signal; a digital CCI encoder 362 for rewriting digital CCI data on the system stream signal in accordance with a command of a system control section 364; an encryption generator 363 for encrypting the system stream by adding an encryption thereto and transferring the encrypted system stream to the recording signal processing section 357; and a system controller 364 which reads the digital CCI data and provides the digital CCI encoder 362 with a command to rewrite the digital CCI data, as well as controls the mechanism control section 356.
Digital recording operation is as follows. The optical pickup 342 reads a signal recorded on the disc 340, and the signal processing section 344 performs data punching and error correcting to extract a system stream digital signal while supplying the mechanism control section 343 with a control signal. The decoder 345 transfers a system stream of which encryption has been decoded from the system stream to the AV decoder 347. The AV decoder 347 extracts a digital audio or digital video signal from the system stream to decode the same, and transfers the decoded signal to the digital signal output control section 349. The digital signal output control section 349 outputs the digital audio or digital video signal while converting it into a signal of a definite output format (such as for example, IEC60958 and IEEE1394).
A definite digital signal inputted from the outside is converted into a digital audio or digital video signal by the digital input converting section 360 and transferred to the AV encoder 361. The AV encoder 361 encodes the digital audio or digital video signal into a system stream. The digital CCI decoder 358 detects digital CCI data from the system stream signal to transfer this digital CCI data to the system control section 364. The system control section 364 reads the digital CCI data and, when necessary, provides the digital CCI encoder 362 with a command to rewrite the digital CCI data on the system stream, and also controls the mechanism control section 356. The system stream is encrypted by the encryption generator 363, and then the recording signal processor 357 adds an error correcting code and perform modulation on the encrypted system stream to output a recording signal to the optical pickup 355 and record the system stream on the recordable disc 353.
Analogue recording operation is as follows. The optical pickup 342 reads a signal recorded on the disc 340, and the signal processing section 344 performs data punching and error correcting to extract a system stream digital signal while supplying a control signal to the mechanism control section 343. The decoder 345 decodes the system stream and transfers the decoded system stream to the AV decoder 347. The AV decoder 347 extracts a digital audio or digital video signal from the system stream to decode the same, and transfers the decoded signal to the DA converter 348. The DA converter 348 outputs the digital audio or digital video signal while converting it into an analogue signal.
When inputted to the optical disc recorder 365, the analogue signal is converted into a digital audio or digital video signal by means of the AD converter 359, and transferred to the AD encoder 361. The AD encoder 361 encodes the digital audio or digital video signal into a system stream. Since an analogue input signal does not include digital CCI data, the digital CCI decoder 358 transfers information to the system control section 364 that digital CCI data is not detected from the system stream signal. The system control section 364 does not issue a command to the digital CCI encoder 362, does note rewrite the digital CCI data on the system stream because there is no digital CCI data, and also controls the mechanism control section 356. The system stream is encrypted by the encryption generator 363, and then the recording signal processor 357 adds an error correcting code and perform modulation on the encrypted system stream to output a recording signal to the optical pickup 355 and record the system stream on the recordable disc 353. The disc on which recording is made in the above manner does not include digital CCI data.
Next, CCI data on the disc file structure of the conventional system will be described with reference to FIG. 19. A disc 369 includes mainly four zones, i.e., VolumeZone, AudioZone, VideoZone and OtherZone, and among which, copy control management information of audio contents and video contents are described on AudioZone 370 and VideoZone 371, respectively.
AudioZone 370 includes a plurality of audio title sets ATS (372), and each audio title set ATS includes an audio title set management information storage area ATSI (373) and an audio data object collection AOBS (374). The audio data object collection AOBS includes a plurality of audio contents as reproduction units and digital CCI data corresponding to the respective reproduction units of audio contents. As shown in FIG. 19, ATS#1 (372) includes ATSI#1 (373) and AOBS (374), and AOBS (374) includes p Track numbers as reproduction units of the audio contents. Likewise, also VideoZone 371 includes digital CCI data with respect to audio/video contents for each Chapter which is a reproduction unit.
Next, CCI data on the object data structure of the conventional system will be described with reference to FIG. 20. FIG. 20 shows an example of audio data. Audio title set collection AOTT_AOBS (380) includes a plurality of audio title sets AOTT_AOB (381). The audio title set AOTT_AOB (381) includes a plurality of audio packs A_PCK (382), and further each audio pack A_PCK (382) includes PrivateHeader (383) and Audio data (385). Then, the Private Header (383) includes a region 384 storing the digital CCI. A plurality of audio packs A_PCK (382) constitute Audio_Cell (386), and assembly of plural Audio_Cell (386) constitutes a Track (387) which is a reproduction unit. In this reproduction unit Track (387), data of the digital CCI (384) is constant and will not change. Conversely, digital CCI data corresponds to a Track unit.
In this object data structure, PTS region in the fifth stair is for storing reproduction time data, sub_stream_id region is for storing stream types, first_access_unit_pointer indicates a first byte of an audio frame of this A_PCT.
Such digital CCI data is included in the form of digital signal data in object data of a disc, however, there is a danger that a person who is familiar with the object data structure can easily tamper with the copy control management data (CCM) detector/rewriter to thereby tamper with the digital CCI data. In addition, there is a problem that once an analogue copy is made, copies of consequent generations are enabled without limitation. Contents providers who produce and provide movie titles and music titles have special fear that digital AV contents data that would get to higher quality in future will be digitally copied illegally in large extent without deteriorating quality thereof.